(a) Field of the Invention
This invention relates to a new electrical switching device especially but not exclusively designed for use in a hold-up alarm system. More particularly, the invention relates to a new electrical switching device comprising a pair of manually operable arms which, when they are pushed simultaneously in, cause a thin flexible blade to bend and press onto a push-button switch located in a casing, thus causing an electrical circuit to be closed or opened and to actuate a remote system, such as an alarm system.
(b) Brief Description of the Prior Art
During any robbery that is in the form of a sudden and quick attack, it is known that the thief and the personnel of the institution being robbed are all subjected to a tremendous amount of nervous tension. Since almost all robberies of this type are made with firearms as intimidating means, it is important that the employees cooperate to protect their lives, without seemingly interfering with the robber's plans. It is however also important that an alarm be given, without attracting the robber's attention. The necessity of having access to an alarm system so constructed and arranged as to avoid arising suspicion in the robber's mind and causing a panic reaction which could eventually become threatening to the personnel's security is well known and evident for everyone.
Several robbery alarm systems have already been constructed to quickly yet quietly close an alarm circuit and thus warn police officials that a robbery is taking place in the building where the alarm system is located.
Alarm systems of this type have been constructed, including a switch actuated by the downward movement of a press-button placed on a floor. The use of such systems is questionable since it is often subjected to be operated unintentionally.
Another type of alarm system has been proposed, including a switch to be actuated by the upward movement of the foot of a cashier or teller. With such systems, inadvertent pressure exerted onto the switch by a foot does not close the circuit and sound the alarm. Such alarm systems are described in U.S. Pat. Nos. 1,496,864 and 2,054,792.
U.S. Pat. No. 4,300,129 discloses another alarm system, including a pull-type switch which normally rests on a trigger pin. When the switch is depressed by the action of a finger, the trigger pin is released and an alarm circuit is closed, thus activating the alarm circuit.
More sophisticated systems have been proposed, comprising a pair of push buttons which selectively sound different call means, when operated singly, or sound an alarm when operated simultaneously. For example, U.S. Pat. No. 4,737,751 describes an alarm system having two independently engageable plungers that must be simultaneously pressed by a cashier or by any other person to activate the alarm circuit.
The main problem associated with the one-button alarm systems is that, in spite of their reliability, they are subject to accidental activation by a cashier during routine, non-emergency situations.
The main problem associated with the two-button alarm systems is that they are rather complicated in structure and thus expensive.